RFC connection between HCC and HCP disconnects

I have a java application, which communicates with SAP system through Hana Cloud Connector. Connection is valid, and I can see requests are returning proper data to HCP.

The problem arises after some time after the first call issued by Java Application. After some time I get errors:

"Opening connection to backend failed: Opening connection denied. Expose the system in your SAP HANA Cloud connector in case it was a valid request."

The point is, that connection is valid, but after some time it seems to be lost.

In destination properties I provided values for peek_limit, pool_capacity, expiration_time and expiration_check_period. As for now, I did not identify why connection is lost. Requests that returns that error code are not listed on HCC, but there are no logs on HCC which will indicate connection refusal.

To clarify, this is a timeline of situation:

I run java app on HCP

I run some RFC calls, which are valid and returns data

After some time, each requests end with error message

After Java app restart on HCP, everything works fine again

The same application works fine on another system, so I think it may be some configuration lack. Do you have any suggestions where can I look for an issue?